Why am I only getting partial streamlines.

Question

Boris Chan 2021-2-17

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/747547-why-am-i-only-getting-partial-streamlines

评论： David Goodmanson 2021-2-17

采纳的回答： David Goodmanson

在 MATLAB Online 中打开

I am trying to plot streamlines to look like this

But I am only getting part way

I have tried changing my sy and sx multiple times but it just changes what part shows up. I have no idea what I'm doing wrong

Here's my code

%% 
[X,Y] = meshgrid(-5:0.5:5); 
sx = linspace(-5,5,20); 
sy = sx;
% sx = (-5:0.5:5); 
% sy = ones(size(sx)); 
 sy = sx./sx; 
% [SX,SY] = meshgrid(sx,sy); 
%let U = e1 & V = e2
U = Y; 
V = X; 
figure()
hold on 
quiver(X,Y,U,V); 
streamline(X,Y,U,V,sx,sy,[0.1,20000]); 

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

David Goodmanson 2021-2-17

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/747547-why-am-i-only-getting-partial-streamlines#answer_625342

在 MATLAB Online 中打开

Hi Boris,

the problem is the line sy = sx./sx which creates a vector of ones for sy. Then every streamline originates at the horizontal line sy =1. Here is an example that draws the streamlines orginating from the left side (upper half) and the top side (left half); the remining two sides are similar.

[X,Y] = meshgrid(-5:0.5:5); 
sx = linspace(0,5,10); 
sx(end) =[];      % eliminate streamlines originating at the corners 
sy = sx;
onx = ones(size(sx));
ony = ones(size(sy));
U = Y; 
V = X; 
figure()
hold on 
quiver(X,Y,U,V); 
streamline(X,Y,U,V,-5*onx,sy,[0.1,20000]);
streamline(X,Y,U,V,-sx, 5*ony,[0.1,20000]);
hold off